<p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><span style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman';">五、计算题</span><span lang="EN-US" style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;"><br/> <p></p></span></p><p></p><p></p><p></p><p></p><p style="LINE-HEIGHT: 150%;"><span lang="EN-US" style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;">1</span><span style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;">、某变电站主变压器<span lang="EN-US">SFL-31500/110</span>额定电压为<span lang="EN-US">110</span>±<span lang="EN-US">4</span>×<span lang="EN-US">2.5%</span>——<span lang="EN-US">2</span>×<span lang="EN-US">2.5%/11kV</span>,问高压侧有几个抽头?若电网电压为<span lang="EN-US">110kV</span>,要得到二次侧<span lang="EN-US">11kV</span>和<span lang="EN-US">10.7kV</span>,问高压侧应分别取用哪个抽头?<span lang="EN-US"><br/> <p></p></span></span></p><p></p><p></p><p></p><p></p><p style="LINE-HEIGHT: 150%;"><span lang="EN-US" style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;"><span style="mso-spacerun: yes;"> </span></span><span style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;">解<span lang="EN-US">: <p></p></span></span></p><p></p><p></p><p></p><p></p><p style="LINE-HEIGHT: 150%;"><span lang="EN-US" style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;"><span style="mso-spacerun: yes;"> </span></span><span style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;">该变压器高压侧有7个抽头<span lang="EN-US"><br/> <p></p></span></span></p><p></p><p></p><p></p><p></p><p style="LINE-HEIGHT: 150%;"><span lang="EN-US" style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;"><span style="mso-spacerun: yes;"> </span></span><span style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;">①当低压侧要得到<span lang="EN-US">11kV</span>电压时,则高压侧在电网<span lang="EN-US">110kV</span>时抽头应是:<span lang="EN-US">K<sub>X</sub>X11=110 <p></p></span></span></p><p></p><p></p><p></p><p></p><p style="LINE-HEIGHT: 150%;"><span lang="EN-US" style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;"><span style="mso-spacerun: yes;"> </span></span><span style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;">∴可取<span lang="EN-US">K<sub>X</sub>=110/11=10<span style="mso-spacerun: yes;"> </span>K<sub>X</sub></span>为<span lang="EN-US">K<sub>5</sub><br/> <p></p></span></span></p><p></p><p></p><p></p><p></p><p style="LINE-HEIGHT: 150%;"><span lang="EN-US" style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;"><span style="mso-spacerun: yes;"> </span></span><span style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;">即第5档<span lang="EN-US"><br/> <p></p></span></span></p><p></p><p></p><p></p><p></p><p style="LINE-HEIGHT: 150%;"><span lang="EN-US" style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;"><span style="mso-spacerun: yes;"> </span></span><span style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;">②要使低压得到<span lang="EN-US">10.7kV</span>时,则高压侧应为:<span lang="EN-US"><br/> <p></p></span></span></p><p></p><p></p><p></p><p></p><p style="LINE-HEIGHT: 150%;"><span lang="EN-US" style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;"><span style="mso-spacerun: yes;"> </span>K<sub>X</sub>X10.7=110 </span><span style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;">∴<span lang="EN-US">K<sub>X</sub>=110/10.7=10.28 <p></p></span></span></p><p></p><p></p><p></p><p></p><p style="LINE-HEIGHT: 150%;"><span lang="EN-US" style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;"><span style="mso-spacerun: yes;"> </span></span><span style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;">因为<span lang="EN-US">U1=11X10.8=112.88(kV) <p></p></span></span></p><p></p><p></p><p></p><p></p><p style="LINE-HEIGHT: 150%;"><span lang="EN-US" style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;"><span style="mso-spacerun: yes;"> </span></span><span style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;">而高压侧在第4档时,<span lang="EN-US">U1=110(1+1X2.5%)=112.75(kV) <p></p></span></span></p><p></p><p></p><p></p><p></p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><span lang="EN-US" style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;"><span style="mso-spacerun: yes;"><font face="Times New Roman"> </font></span></span><span style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman';">两者接近</span><span lang="EN-US" style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;"><span style="mso-spacerun: yes;"><font face="Times New Roman"> </font></span></span><span style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman';">∴取</span><span lang="EN-US" style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;"><font face="Times New Roman">K<sub>X</sub>=K<sub>4 <p></p></sub></font></span></p><p></p><p></p><p></p><p></p><p class="MsoPlainText" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><span lang="EN-US" style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;"><span style="mso-spacerun: yes;"></span></span><sub><span lang="EN-US" style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;"></span></sub></p><p></p><p class="MsoPlainText" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><span lang="EN-US" style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;">2</span><span style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;">、某企业变电站、配变容量<span lang="EN-US">3200kVA,35/10.5kV</span>,供电总负荷<span lang="EN-US">3000kW</span>,<span lang="EN-US">COS.</span>φ<span lang="EN-US">1=0.6</span>,如果满足全部负载用电时,变压器实际负荷多大?若将<span lang="EN-US">COS.</span>φ<span lang="EN-US">1</span>提高到<span lang="EN-US">COS.</span>φ<span lang="EN-US">2=0.95</span>,需补偿无功容量多大?此时该变压器能否满足运行需要?<span lang="EN-US"><br/> <p></p></span></span></p><p></p><p></p><p></p><p></p><p class="MsoPlainText" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><span style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;"> <span lang="EN-US">. </span>解<span lang="EN-US">: <p></p></span></span></p><p></p><p></p><p></p><p></p><p class="MsoPlainText" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><span lang="EN-US" style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;"><span style="mso-spacerun: yes;"> </span></span><span style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;">∵<span lang="EN-US">=SCOS</span>φ<span lang="EN-US"><br/> <p></p></span></span></p><p></p><p></p><p></p><p></p><p class="MsoPlainText" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><span lang="EN-US" style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;"><span style="mso-spacerun: yes;"> </span></span><span style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;">∴变压器实际负荷为:<span lang="EN-US">S=P/COS</span>φ<span lang="EN-US">1=3000/0.6=1800kVA <p></p></span></span></p><p></p><p></p><p></p><p></p><p class="MsoPlainText" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><span lang="EN-US" style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;"><span style="mso-spacerun: yes;"> </span><p></p></span></p><p></p><p></p><p></p><p></p><p class="MsoPlainText" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><span lang="EN-US" style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;"><span style="mso-spacerun: yes;"> </span></span><span style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;">若将<span lang="EN-US">COS.</span>φ<span lang="EN-US">2</span>提高到<span lang="EN-US">0.95</span>,则应补偿无功功率为:<span lang="EN-US"><br/> <p></p></span></span></p><p></p><p></p><p></p><p></p><p class="MsoPlainText" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><span lang="EN-US" style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;"><span style="mso-spacerun: yes;"> </span>Q<sub>C</sub>=P[tg</span><span style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;">φ<span lang="EN-US">1-tg</span>φ<span lang="EN-US">2] <br/></span></span></p><p class="MsoPlainText" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><span style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;"><span lang="EN-US"><strong><font face="" size="3"></font></strong></span></span></p><p class="MsoPlainText" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><span style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;"><span lang="EN-US"></span></span></p><p class="MsoPlainText" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><span style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;"><span lang="EN-US"></span></span><span lang="EN-US" style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;"><span style="mso-spacerun: yes;"> </span>=3000(1.333-0.328) <p></p></span></p><p></p><p></p><p></p><p></p><p class="MsoPlainText" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><span lang="EN-US" style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;"><span style="mso-spacerun: yes;"> </span>=3016(</span><span style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;">千乏<span lang="EN-US">) <p></p></span></span></p><p></p><p></p><p></p><p></p><p class="MsoPlainText" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><span lang="EN-US" style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;">S2=P/COS</span><span style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;">φ<span lang="EN-US">2=3000/0.95=3157</span> <span lang="EN-US">KVA <p></p></span></span></p><p></p><p></p><p></p><p></p><p class="MsoPlainText" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><span lang="EN-US" style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;">S2</span><span style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;"><<span lang="EN-US">S</span>额<span lang="EN-US"><br/> <p></p></span></span></p><p></p><p></p><p></p><p></p><p class="MsoPlainText" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%;"><span style="FONT-SIZE: 14pt; LINE-HEIGHT: 150%;">所以能满足运行要求<span lang="EN-US"><br/> <p></p></span></span></p><p></p><p></p><p></p><p></p><br/>
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